Honors Physical Science S2 Review
Name: ____________________
Pd: ____ Date: __________
Conservation of Mass
1.) A student decides to dissolve granulated sugar in water to see if the mass changes.
a.) When sugar dissolves in water, do you predict a change in mass? Explain why or why not.
No, because mass never is created or destroyed—Law of Conservation of Mass
b.) When the sugar dissolves and “disappears”, is the sugar still there? List at least two possible ways to prove
whether or not the sugar is still in the water.
Yes. You can boil away the water and be left with sugar. You could also taste the water.
c.) The student adds 4.0 grams of sugar to 18.0 grams of water. Make a prediction of the combined mass of the two
substances. Explain the reasoning behind your prediction.
22.0 grams; because mass never is created or destroyed—Law of Conservation of Mass
d.) Predict: The volume of dissolved sugar is ( more / less ) than solid sugar. Explain your prediction.
Less; because the air spaces in between each sugar crystal are now taken up by water so the volume of the sugar
appears to decrease.
e.) The volume of the sugar was 5.0 mL and the volume of the water 18.0 mL. Between what two numbers can we be
absolutely certain the combined volume of the two substances will be? Explain why you chose these two numbers.
18.0 ml – 23.0 ml. The combined volume of the sugar and the water cannot be less than the water alone nor more
than the total combined of the sugar and water.
f.) The student does the lab and obtains the following results.
mass before mixing: 22.00 grams
Calculate: ∆m = -0.02 grams
mass after mixing: 21.98 grams
g.) From the above data and calculations, the student draws the conclusion that when sugar dissolves, mass must
change because there was a measured change. Think of two reasons why this is not a valid conclusion to make.
Reason #1:
Loss of sugar crystals or water when mixed.
Reason #2:
Error within the balance itself.
2.) Provide an explanation in your own words of what it means to say that “Mass is Conserved”.
3.) Is mass ever created or destroyed when a substance:
a.) dissolves?
b.) melts?
NO
c.) precipitates?
NO
d.) produces a gas?
NO
NO
4.) What is a closed system? When trying to find the change in mass during various processes, why is it important to
do so in a closed system?
When the system is not open to the environment. So that no mass is lost to the environment.
Characteristic Properties
5.) Ethanol has a density of 0.789
g
cm 3
6.) All pure gold has a density of 19.4
. What is the mass of 225 cm3 of ethanol? 225 x 0.789 = 177.525 grams.
g
1 cm 3
. A particular cube of gold measures 4.23 cm on each edge. What is the
volume of the cube? What is its mass? V = 4.23 x 4.23 x 4.23 = 75.69 cm3 Mass = 75.69 x 19.4 = 1468.33 g
7.) While in the lab your group collects 180cm3 of CO2 from the combination of water and Alka-Seltzer. You
calculate the mass difference before and after the test to be 0.36 grams. What is the density of the CO2 gas? How
much space would 10 grams of the CO2 gas fill? D = 0.36 g/180 cm3 = 0.002 g/cm3
0.002 g/1 cm3 = 10 g/ ??? cross-multiply and divide = 5000 cm3
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8.) A substance was placed in an oven at 125 ˚C. According to the
graph at right that shows the relationship between time and
temperature for the heating of a single substance, at what temperature
does the substance:
a.) freeze and melt? -5
Sample Temp. vs Time
125
105
85
Temperature (ÞC)
b.) boil and condense? 106
c.) At what temperature is the substance both a solid and a liquid?
-5
d.) At what temperature is the substance both a liquid and a gas?
106
e.) Between what temperatures is the substance completely a:
i.) solid?
ii.) liquid?
iii.) gas?
-15 to -5
-5 to 106
106 to 125
65
45
25
5
-15
0
5
10
15
20
Time (30 sec intervals)
9.) In Lab 3.11, you found the density of the gas produced when Alka-Seltzer reacts with water. How would your
measured density be different if you had used:
a.) twice as much Alka-Seltzer? Why?
It would be the same because density is a characteristic property and does not change.
b.) half as much Alka-Seltzer? Why?
It would be the same because density is a characteristic property and does not change
10.) What could be a typical density for a:
a.) solid? Around 2.0
11.) The density of liquid A is
b.) liquid? About 1.0
c.) gas? Much less than 1.0
2.0 g
1.5 g
and the density of liquid B is
. If you had 100 cm3 of liquid A, how
3
3
1 cm
1 cm
many cm3 of liquid B would you need in order to have an equivalent amount of mass? 133.33 cm3
Solubility
12.) What is concentration? What is a saturated solution? What is solubility?
Concentration is the measurement of the amount of solid dissolved in a specific amount of liquid at a specific
temperature. A saturated solution is where no more solid will dissolve in a liquid at a specific temperature. Solubility
is the range of amount of solid that will dissolve in a certain amount of liquid over a range of temperatures.
13.) A student adds 8.0 g of a solid and 15.0 g of water to a test tube and shakes the tube for 5 minutes. Not all of the
solid dissolves. The student then pours the resulting solution (only the liquid) into a massed evaporating dish. The
combined mass of the evaporating dish and the solution now in the dish is measured. After the water has been
evaporated away, the mass of the dish and the remaining solid is found.
a.) Was the solution that was poured into the evaporating dish saturated? How do you know?
b.) Using this data:
Mass of evaporating dish:
Mass of dish and solution:
Mass of dish and remaining solid:
23.98 g
29.72 g
25.22 g
i.) What was the mass of the remaining solid (the solid dissolved in the solution, the solute)? 25.22-23.98=1.24g
ii.) What was the mass of the water (the solvent)? 29.72 – 25.22 = 4.50g
iii.) What is the density of water?
1.0 g/cm3
iv.) What was the volume of the water (the solvent)? 4.50 cm3 (same as mass)
v.) What was the concentration of the solution in g / 1 cm3? .28
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14.) How does temperature affect the solubility of a gas in a liquid? Compare this to how temperature affects the
solubility of a solid in a liquid.
Increased temperature causes gas to be less soluble in liquid. Increased temperature causes a solid to be more
soluble in a liquid.
15.) Using the graph on p.71 of your text, what is the maximum amount of potassium nitrate that could dissolve in:
a.) 100 cm3 of water at 65ºC?
b.) 200 cm3 of water at 65ºC?
c.) 200 cm3 at 85ºC?
130g
260g
~364g
16.) Using the graph on p.71 of your text, suppose you place 150 g of potassium nitrate and 100 g of sodium nitrate in
a beaker that contains 100 cm3 of water. Assume they have no affect on how each other dissolve. What is the lowest
temperature at which all the potassium nitrate and sodium nitrate will dissolve?
74ºC
Atomic Structure
17.) Complete the following table.
Element
Protons
Neutrons
Electrons
Nitrogen
7
7
7
Atomic
Weight
14
Sodium
11
21
11
23
Neon
10
10
10
20
18.) Fro each atom, draw the electrons for
each shell and fill in the missing data.
Atomic
Number:
Li
C
O
_3_
_
_6_
_
_8_
_
Total e-:
19.) a.) For each element in the below table, fill in the cation
that the atom forms.
b.) Provide one example of a monatomic ion (e.g.: F1-, Cl1-,
O2-, N3-, etc.) with which the cation could react in order to
form an ionic compound. Name the compound.
.
Element
Cation
Sodium
Na1+
_3_
_8_
_6_
_
_
_
Valence e-:
_1_
_6_
_4_
_
_
_
Electron
2 1
2 2
4
2 2
2
Config.: _1s 2s __ _1s 2s 2p _ __1s 2s 2p _
_____
______
_____
Ionic
charge:
_+1__
F1-
Ionic Compounds
(Formula)
NaF
CO32-
Na2CO3
Anions
_+/-4__
_-2__
Magnesium
Potassium
Copper (I)
(cuprous)
we
will
do
this
in
Silver
Class.
Zinc
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20.) Complete the following table.
Compound
Name
Formula
Molar Mass
Mass
Moles
Molarity
.336/.05L
Calcium
chloride
CaCl2
110.98g/mol
37.3g
.336 mol
Copper (II)
nitrate
Cu(NO2)2
155.556g/mol
1240 g
7.971 mol
6.72 M
7.971/.900
8.86 M
250 ml
Copper (II)
acetate
Cu(C2H3O2)2
181.633g/mol
18.16g
0.100 mol
0.40 M
Compound Synthesis and Decomposition
21. What is a compound? Also, explain how it differs from an element.
A compound results when two, or more, elements combine together (bond), forming a new pure substance.
22. What is a pure substance? Also, explain how it differs from a mixture.
All the particles of a pure substance have identical characteristic properties whereas particles in mixt. differ.
23.) What is the Law of Constant Proportions?
It states that when compounds are either synthesized or decomposed, they always do so in specific ratios.
24.) If a student collected 30 cm3 of hydrogen during the decomposition of water:
a.) How many cm3 of oxygen would be collected? 15
b.) Does the volume of the water equal the volume of the two gases? Why/why not? No- diff densities.
c.) If the H were recombined with the O, would there be more mass, same amount of mass or less mass than
the mass of the original H2O would result? Explain your answer. Same! Conservation of mass.
25.) What are three ways that radioactive elements are the same as ordinary elements?
i.) compounds form with constant proportions ii.) characteristic densities, melting & boiling points, etc.
iii.) cannot be decomposed by heating, electricity, or by reacting with acid
26.) How is the decomposition of a compound different than radioactive decay? Provide two examples.
Compound decomp., the elements stay the same and don’t emit particles. NaClO 3NaCl+O2 & H2OH2+O2
27.) What is an α-decay? What is a β-decay? What causes a γ-ray to be emitted?
α-decay: 2 protons&2 neutrons (α-particle) emitted; β-decay: proton becomes neutron and emits electron (β-particle);
γ-ray emitted b/c high energy nucleus “drops” to lower energy level, high energy photon emitted
28.) What is half-life? What does it tell you? Is it a characteristic property? Explain. The time it takes ½ the sample
to decay and it is a char. prop., each radioactive element takes a different amount of time to decay.
Bonding
25.
Why do atoms combine to form molecules?
To complete their valence shells by either sharing or transferring electrons
26.
What is a chemical bond?
The attraction between atoms resulting from electron interactions.
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27.
What’s the difference between a covalent bond and an ionic bond?
Covalent- Sharing electrons Ionic- complete transfer of electrons.
28.
Why does one oxygen atom combine with two hydrogen atoms to form water?
Oxygen needs 2 more electrons to complete valence shell. 2 hydrogen atoms each have one to share.
29.
30.
31.
What are typical traits of ionic compounds? What are ionic compounds often called?
High melting points, crystalline structure, etc.
“Salts”
Explain electronegativity and why it determines if a bond is nonpolar covalent, polar covalent, or
ionic.
Electronegativity is the relative affinity an element’s atom has for electrons.
If difference is less than .4 = nonpolar covalent ; between .4 & 1.7 = polar covalent ; over 1.7 = ionic
Complete the following table.
Molecule
O2
H2 O
BeCl2
NH3
KF
N2
CO2
C4H10
Ionic or
Covalent?
Covalent
Covalent
Ionic
Covalent
Ionic
Covalent
Covalent
Covalent
Total
Valence
Electrons
12
8
16
8
8
10
16
24
Lewis dot
structure
See
Your
Teacher
When
You
Get
To
Class
Acids & Bases
32. What makes an acid, an acid? What makes a base, a base?
Acids add extra Hydrogen Ions to water solution, bases add extra hydroxides.
33. While doing a lab, you are able to determine that there is 10-5 moles of H+ in one liter of the solution.
What is the pH of this solution? Would you consider this solution an acid or a base? Why?
5
Acid- pH is less than 7
34. While doing another lab, you measure the pH of solution A to be 3. You measure the pH of solution B
to be 6. How many times more acidic is solution A from solution B?
1000x
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